Piston, and piston and connecting rod assembly



Jan. 18, 1938. R. K. LEE 2,105,743

PISTON, AND PISTON AND CONNECTING ROD ASSEMBLY Filed May 19, 1934 INVENTOR. 770562" /1. lee.

ATTORNEYS.

TED

PISTON, AND IPIS'ION AND CONNECTING ROD ASSTELY Roger K. Lee, Highland Park, Mich assignor to Chrysler Corporation, Detroit, Mich, a corporation of Delaware Application May 19, 1934, Serial No. 726,487

2 Claims. (Cl. 309-16) This invention relates to internal combustion Fig. 1 is a sectional elevational view of my pisengines and refers more particularly to improveton and connecting rod assembled as an operatments in pistons, and piston and connecting rod ing unit, the section being taken along the line assemblies. l--| of Fig. 2. 1

This application is directed to improvements in Fig. 2 is a top plan view of the piston shown in the subject matter set forth in my co-pending Fig. 1. application Serial No. 726,486, filed May 19, 1934, Fig. 3 is a fragmentary sectional elevational the latterbeing a division'of my co-pending apview along the line 3--3 of Fig, 2.

QFF'ME plication Serial No. 657,146, filed February 16, Fig. 3A is a fragmentary sectional view illus- 1933. trating the manner of securing the locking pins 10 One object of my invention is to provide a pisin position. ton, and piston and. connecting rod assembly of Fig. 4 is a view similar to Fig. 3 illustrating the improved characteristics whereby the engine may manner of assembly of the connecting means for be successfully operated at speeds materially the piston pin bosses.

higher than the usual speeds of conventional en- Fig. 4A is a partial top plan view of the piston 15 gines used for driving motor vehicles, for examas shown in Fig. 4. ple. While my improved piston, and piston and r Fig. 5 is a bottom plan view of the piston forgconnecting rod assembly are not necessarily liming prior to the assembly of the piston pin.

ited in their application to such high speed n- Fig. 6 is a side elevational view of the connectgines, my improvements are particularly adapted g rod a d piston D assembly, a Portion of to such applications. piston being broken away.

A further object of my invention is to provide Fig. '7 is a top plan view of the connecting rod an improved piston structure of unusually light and piston pin assembly as shown in Fig. 6. weight, at the same time affording the strength Referring to the drawing, reference character 5 requisite for high speed operation. A represents the piston, B the piston pin bosses,

A further object of my invention is to provide and C the connecting rod and piston pin assem- F an improved method of assembly for the com- 3'- ponent piston parts and for the piston and cone piston A comprises the Cylindrical eed necting rod. portion 80 and cylindrical skirt portion ll pref- 39 Another object of myinvention is to provide erably forged. to as a Unit from durelllmin an improved piston construction which, under o he Su bl lightweight oy having t e the temperatures and other operating conditions, qu te Strength. The d is p ov ed W th will not produce local stremes and distortions t a sv y Spaced y al bores $2 a d 3 heretofore giving rise to oil pumping and leak extending therethrough, these bores each having age, relief of oil cushion, piston slap,piston wear? an nl c n r p n r co n re and other objectionable commonly experienced M ferming an annular Shoulder l5 p ed characteristics. I preferably provide a cylindril/ from e Piston pp Outer ace Hical' piston skirt free from boss openings, slots, The bores l2 and 53 have their axes parallel with perforations and the like which have heretofore e ax s of the piston a lying in a plane m largely contributed to the aforesaid objectiontaining the PiStOIl eXiS. 40 able characteristics. The cylindrical skirt l l depends from the head In order to realize the improvements afiorded ill a d is Preferably imperfolate. being free om by my piston, I have further provided improved s Openings, Slots, perforations, d e l ke. means for attaching the piston head, the bosses Thus, e Skirt maintains a d time fit w fi and head being preferably formed of the sam the cylinder without tendency to destroy the dematerial or materials having th am coeffisired oil film. Heretofore it has been customary cients of expansion whereby the piston parts will to provide p s slots in e s t of p not relatively separate. Such separation in pistons but this results in relief of the oil film with tons subjected to unusually high speed operaaccompany Piston p and undue Wear of t e tions would quickly give rise to piston failures. piston and cylinder rubbing surfaces. Further- 50 Further objects and advantages of my invenmore the aforesaid conventional openings, slots, tion will be more apparent from the following deand. the like produce local stresses and distortailed description of one illustrative embodiment tions in the piston when subjected to the operatthereof, reference being had to the accompanying temperatures, and this in turn results in a ing drawing, in which: tendency to oil pumping which requires a rela- 55 tively large number of sealing rings to check the escape of oil. Each added sealing ring materially lowers the power output of the engine by reason of the additional friction loss and wear occasioned by the ring expanding against the cylinder.

As shown in Fig. 5 the underface of the piston is preferably provided with a series of transversely extending inwardly projecting fins or ribs ll. Certain of the ribs l'l extend from points adjacent the bores l2 and I3 toward the skirt II, the ribs serving to facilitate cooling of the piston and also to add rigidity to the piston structure. For additional strengthening of the structure and to avoid sharp weakening corners, the inner wall of skirt H may be chamfered at l6 to form the juncture between this inner wall and the underface of the piston.

The piston head l as herein illustrated has a plurality of annular grooves I6 preferably two in number for accommodating the piston rings 20. In my aforesaid co-pending applications the pistons described therein carry only a single piston ring and, if desired, a single ring may be used in my subject piston since certain generic features of my pistons render the use of a large number of rings unnecessary.

Fitting within each of the bores l2 and Ills a. forged duralumin piston pin boss B, each having an outwardly extending reduced threaded portion or post 2i adapted to threadedly receive the nut D as viewed in Fig. 4 prior to the final machining of the piston face. The threaded portions 2| preferably project substantially to they B as the nuts D are tightened.

The bosses B project inwardly of the piston head within skirt II to provide co-axial piston pin bearings or openings 24 adapted to receive.

the cylindrical end bearing portions 26 of the and the nuts reacting on the shoulders 05 as viewed in Fig. 4. The holes-21 are then drilled inwardly of the piston face opposite the flats 22' at the contact between the bosses B and the enlarged openings l4 as shown in Fig. 3. Retaining or looking pins 28 preferably also of duralumin are then forced into the holes 21, the upper ends of the pins preferably lying slightly inwardly from the face of the piston. The edges of the holes 21 are then staked in at several points with a punch as indicated at 29 in Figs..3A and 4 to lock the retaining pins in place. When the piston face is finally machined along the line X-X the punch depressions are removed, suflicient material being left'overhanging the ends of pins 28 to hold them securely in place as shown in Fig. 3.

During the final machining operation along the line X-X the wrench ends of the nuts D and the outer ends of the threaded reduced portions 2| are also cut off flush with the piston face, the

final assembly being shown in Figs. 1 to 3, inclusive, and Fig. 6. If desired, the wrench ends of nuts D may be removed prior to drilling the holes 21 in which instance the final machining of the piston face will remove the outer extremities of the threaded portions 2| simultaneously with the removal of the punch depressions. In this manner the bosses B are properly located and securely attached to the head l0 against any relative displacement, the nuts D being prevented from turning when the piston is in operation. If desired, the bosses B may be provided with openings 30 for admitting lubricant to the pin bearings 25 associated therewith. A piston constructed in the above manner presents a substantially smooth uninterrupted upper face portion free from objectionable pockets or recesses which, when present, will carbonize and decrease engine operating efllciency.

It will be apparent that the connecting rod including the T-shaped piston pin 26 will be securely held assembled with the piston and since the pin 26 and bosses B are machined and assembled before connection to the piston head, the desired accurate alignment of the parts is provided.

The connecting rod assembly C, by itself and apart from its novel cooperative relationship with the piston, forms the subject matter of my copending application Serial No. 730,434, filed June 13, 1934. This connecting rod structure is preferably of forged steel and comprises the lower bearing portion 3| and the upper piston pin portion 32. This assembly is constructed for a maximum of strength and a minimum of weight.

The piston pin portion 32has a bore 33 extending through the pin 26 and the rod portion at right angles thereto also has a bore 34 axially thereof, these bores communicating by an oil hole 35. A'reinforcing flange 36 extends from the rod portion and surrounds the upper central portion of the pin 26 for strengthening the T- joint formed by the pin and rod portions.

The lower end of the rod portion has a cylindrical bearing 31 adapted on assembly with the bearing portion 3| to closely fit in the upwardly opening socket 31', the joint thus formed being copper hydrogen welded to form a permanent structure.

Below the socket 3'! the bearing portion 3! has an enlarged portion of relatively thin cross section in the direction transversely of pin 26 to provide the opening 38. This opening receives a bushing 39 and the latter in turn receives the crank pin (not shown). A strengthening flange 40 extends outwardly preferably from opposite sides of the upper sockets end 3'! and around the opening 38. Extending at right angles to the flange 40 the opening 38 is bounded on each side of the bearing portion 30 with an annular web or flange 4| and the spaced flanges or ribs 42, 43 extend between the lower end of the socket 3! to the flange 4!.

What I claim is:

1. In a piston having head and skirt portions, a piston pin receiving boss having a portion thereof extending through said head portion, a cylindrical securing member threaded on said extended boss portion, the outer face of said head portion having a cylindrical recess closely receiving said securing member, and a locking pin engaging the contacting cylindrical surfaces of said extended portion and said recess, a portion of the wall of said recess overhanging the ad- Jaccnt end of said pin, said securing member and said pin presenting in conjunction with said head portion a substantially uninterrupted flat face therefor.

2. The method of securing a piston pin boss to a piston consisting in clamping the boss in position by a clamping element having .9. tool engageabie portion adapted to be sheared of! upon the application of force when said boss is clamped in position, inserting a pin in the piston and in looking engagement with the clamping element, deforming a portion 0! the piston inwardly thereof adjacent the pin to secure the pin in place, and machining an outer surface of the piston to substantially remove the irregularities incident to saigl deformation and shearing of said clamping element for providing a substantially smooth uninterrupted piston face.

ROGER K. LEE. 

